Ruthenium-based triazole carbene complexes

ABSTRACT

The present invention relates to novel ruthenium-based triazole carbene complexes comprising specific ligands, their preparation and their use as catalysts in hydrogenation processes. Such complex catalysts are inexpensive, thermally robust, gel formation inhibiting and olefin selective.

FIELD OF THE INVENTION

The present invention relates to novel ruthenium-based triazole carbenecomplexes comprising specific ligands, their preparation and their useas catalysts in hydrogenation processes.

BACKGROUND OF THE INVENTION

In Ind. Eng. Chem. Res. 1991, 30, 1086-1092, Macromolecules 1992, 25,883-886, J. Mol. Catal. A:Chem. 1998, 135, 121-132 and Rubber Chem.Technol. 2008, 81, 227-243 the Rhodium-based catalysttris(triphenylphosphine)rhodium(I)chloride of formula (1) is disclosedfor hydrogenation and hydrosilylation reactions of rubbers. However,high costs are associated with this catalyst which additionally requiresthe use of triphenylphosphine as co-catalyst. The catalyst degrades at145° C.

In Chem. Comm. 1967, 305-306, Chem. Eur. J. 2010, 16, 12214-12220 andTetrahedron Lett. 1966, 4871-4875 it is disclosed, that the complextris(triphenylphosphine) hydrido ruthenium chloride of formula (2) canbe used in a transfer hydrogenation for converting alkynes to alkenes.However, such catalyst does not efficiently hydrogenate nitrile rubbersand it is not selective for only olefins.

In J. Am. Chem. Soc. 1961, 83, 1262-1263, Chem. Eur. J. 2010, 16,12214-12220, Am. Chem. Soc. 2010, 132, 16756-16758 and J. Mol. Catal.A:Chem. 2003, 206, 13-21 the catalyst of formula (3) as shown below isused as a transfer hydrogenation catalyst for alkynes to alkenes and forhydrogenation of amides to alcohols and amines under H₂. However, such acatalyst is not selective for olefins and contains a CO group.

In Organometallics 2006, 25, 99-110, Dalton Trans. 2008, 2603-2614,Organometallics 2009, 28, 1758-1775, Inorg. Chim Acta. 2010, 363,625-632 and Organometallics, 2010, 29, 5450-5455 the catalyst of formula(4) as shown below is prepared from RuHCl(CO)(AsPh₃)₃ and IMes₂. Suchpreparation method, however, is not favorable due to the presence ofAsPh₃. The catalyst further contains a CO group. Such catalyst isdescribed for transfer hydrogenation of aromatic ketones with alcohols.It also hydrogenates olefins and ketones using H₂, however, it is notselective for olefins.

According to Organometallics 2004, 23, 86-94, the catalyst of formula(5) as shown below can be prepared from RuHCl(PPh₃)₃ and two equivalentsof SIMes₂ with the formation of SIMes₂HCl as a by-product. However, nohydrogenation data is reported. It is not possible to displace PPh₃ withSIMes₂ without CH activation of the methyl groups.

In Dalton Trans., 2013, 42, 2362-2365 the catalyst of the formula (6) asshown below is prepared from [(p-cymene)RuCl₂]₂ and a triazolium saltwith following treatment with K₂CO₃ in THF under reflux. However, nohydrogenation data is reported. A specific use for these1,2,3-triazol-5-ylidene (tzNHC) ruthenium complexes is not disclosed inthe paper.

Similar complexes with different metals and different ligands have beendisclosed in the past.

In Dalton Trans., 2012, 41, 13074-13080 the catalyst of the formula (7)as shown below is prepared from IrCl₂(Cp*)(trz) (trz=triazolylidene) andsodium acetate under nitrogen. This iridium complex displays highpotential as a water oxidation catalyst. The use as a hydrogenationcatalyst is not disclosed. The use of other metals like ruthenium isalso not suggested.

In Angew. Chem. Int. Ed. 2010, 49, 9765-9768 the catalyst of the formula(8) as shown below is prepared from [(Cp*IrCl₂)₂] (Cp*=C₅Me₅), Ag₂O anda pyridinium-functionalized triazolium salt. Iridium(III)cyclopentadienyl complexes are described to exhibit excellent activityin electrochemical induced water oxidation. However, no hydrogenationdata is reported. Ruthenium-based complexes are neither disclosed norsuggested.

In Organometallics 2011, 30, 1689-1694 the catalyst of the formula (9)as shown below is prepared from Pd(OAc)₂ and a trans mono nuclear silvercarbene complex [(Tz)₂Ag](Tz=1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene). However, nohydrogenation data is reported.

Summing up various complexes, which are used as catalysts, are alreadyavailable for hydrogenation reactions. However, many of them containunfavorable or expensive ligands, like PPh₃, form gels, are difficult toprepare, are not sufficiently active and/or selective.

Therefore, it was the object of the present invention to provide aninexpensive, thermally robust, gel formation inhibiting and olefinselective novel catalyst for hydrogenation reactions, particularly forhydrogenating polymers, and even more particularly for hydrogenatingnitrile rubbers.

SUMMARY OF THE INVENTION

The above-mentioned objects have now been solved by providing novelruthenium-based complexes according to general formula (I)

-   wherein-   R is independently of one another hydrogen, hydroxy, thiol,    thioether, ketone, aldehyde, ester, ether, amine, imine, amide,    nitro, carboxylic acid, disulphide, carbonate, isocyanate,    carbodiimide, carboalkoxy, carbamate, halogen, straight-chain or    branched C₁-C₁₀-alkyl, preferably methyl, ethyl, n-propyl,    iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl,    C₆-C₂₄-aryl, preferably phenyl, or together with the carbon atoms to    which they are bound form a C₆-C₁₀-cycloalkyl or C₆-C₁₀ aryl    substituent, alkyl thiolate, aryl thiolate, B(R³)₂ or B(R³)₃,    whereas R³ is alkyl, aryl, alkoxy or aryloxy or CF₃,-   n is 0 to 4, preferably 0 to 2, more preferably 0 to 1-   R¹ is straight-chain or branched C₁-C₁₀-alkyl, preferably methyl,    ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl,    tert-butyl, or neopentyl, C₃-C₁₀-cycloalkyl, preferably cyclohexyl    or adamantyl, C₆-C₂₄-aryl, preferably phenyl,    C₁-C₁₀-alkylsulphonate, preferably methanesulphonate,    C₆-C₁₀-arylsulphonate, preferably p-toluenesulphonate,    2,4,6-trimethylphenyl (Mes) or 2,4,6-triisopropylphenyl (Trip),-   R² is hydrogen, straight-chain or branched C₁-C₁₀-alkyl, preferably    methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl    tert-butyl or neopentyl, C₃-C₁₀-cycloalkyl, preferably cyclohexyl or    adamantyl, C₆-C₂₄-aryl, preferably phenyl, C₁-C₁₀-alkylsulphonate,    preferably methanesulphonate, C₆-C₁₀-arylsulphonate, preferably    p-toluenesulphonate, 2,4,6-trimethylphenyl (Mes) or    2,4,6-triisopropylphenyl (Trip),-   X is an anionic ligand, and-   Y¹ and Y² are identical or different and are each    C₁-C₁₀-alkylphosphine or C₃-C₂₀-cycloalkylphosphine ligand,    preferably tricyclohexylphosphine (PCy₃), a sulfonated    C₁-C₁₀-alkylphosphine ligand, a C₁-C₁₀-alkylphosphinite ligand, a    C₁-C₁₀-alkylphosphonite ligand, a C₁-C₁₀-alkyl phosphite ligand, a    C₁-C₁₀-alkylarsine ligand, a C₁-C₁₀-alkylamine ligand, a substituted    or not substituted pyridine ligand, a C₁-C₁₀-alkyl sulfoxide ligand,    a C₁-C₁₀-alkyloxy ligand or a C₁-C₁₀-alkylamide ligand, each of    which may be substituted by a phenyl group which may in turn be    substituted by a halogen, C₁-C₅-alkyl or C₁-C₅-alkoxygroup.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an FT-IR spectrum of a nitrile rubber before hydrogenation.

FIGS. 2 and 3 show FT-IR spectra of the nitrile rubber afterhydrogenation in the presence of catalysts according to embodiments ofthe invention

DETAILED DESCRIPTION OF THE INVENTION

The novel ruthenium-based triazole carbene catalysts are excellentlysuited for hydrogenation reactions, are thermally robust, gel formationinhibiting, use less expensive ruthenium as transition metal and/or areselective for olefin hydrogenation.

Ligand Definition:

In the catalysts of the general formula (I), R is, independently of oneanother, hydrogen, hydroxy, thiol, thioether, ketone, aldehyde, ester,ether, amine, imine, amide, nitro, carboxylic acid, disulphide,carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, halogen,straight-chain or branched C₁-C₁₀-alkyl, preferably methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl,C₆-C₂₄-aryl, preferably phenyl, or together with the carbon atoms towhich they are bound form a C₆-C₁₀-cycloalkyl or C₆-C₁₀-arylsubstituent, alkyl thiolate, aryl thiolate, B(R³)₂ or B(R³)₃, whereas R³is alkyl, aryl, alkoxy or aryloxy or CF₃.

All the above mentioned substituents as meanings of R can be substitutedby one or more further substituents selected from the group consistingof straight-chain or branched C₁-C₁₀-alkyl, C₃-C₈-cycloalkyl,C₁-C₁₀-alkoxy, C₆-C₂₄-aryl and a functional group selected from thegroup consisting of hydroxy, thiol, thioether, ketone, aldehyde, ester,ether, amine, imine, amide, nitro, carboxylic acid, disulphide,carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen.

In the catalysts of the general formula (I), n is 0 to 4, preferably 0to 2 and more preferably 0 to 1.

In the catalysts of the general formula (I), R¹ is straight-chain orbranched C₁-C₁₀-alkyl, preferably methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, sec-butyl, tert-butyl or neopentyl,C₃-C₁₀-cycloalkyl, preferably cyclohexyl or adamantyl, C₆-C₂₄-aryl,preferably phenyl, C₁-C₁₀-alkylsulphonate, preferably methanesulphonate,C₆-C₁₀-arylsulphonate, preferably p-toluenesulphonate,2,4,6-trimethylphenyl (Mes) or 2,4,6-triisopropylphenyl (Trip).

In the catalysts of the general formula (I), R² is hydrogen,straight-chain or branched C₁-C₁₀-alkyl, preferably methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl orneopentyl, C₃-C₁₀-cycloalkyl, preferably cyclohexyl or adamantyl,C₆-C₂₄-aryl, preferably phenyl, C₁-C₁₀-alkylsulphonate, preferablymethanesulphonate, C₆-C₁₀-arylsulphonate, preferablyp-toluenesulphonate, 2,4,6-trimethylphenyl (Mes) or2,4,6-triisopropylphenyl (Trip).

All the above mentioned substituents as meanings of R¹ and R² can besubstituted by one or more further substituents selected from the groupconsisting of straight-chain or branched C₁-C₁₀-alkyl, in particularmethyl, C₃-C₈-cycloalkyl, C₁-C₅-alkoxy, C₆-C₂₄-aryl and a functionalgroup selected from the group consisting of hydroxy, thiol, thioether,ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylicacid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy,carbamate and halogen.

In a preferred embodiment, R¹ and R² are identical or different and areeach methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl,tert-butyl or, neopentyl, cyclohexyl, adamantyl, phenyl,C₁-methanesulphonate, p-toluenesulphonate, 2,4,6-trimethylphenyl (Mes)or 2,4,6-triisopropylphenyl (Trip).

In a more preferred embodiment, R¹ and R² are identical or different andare each methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl,sec-butyl, tert-butyl or cyclohexyl, phenyl, 2,4,6-trimethylphenyl (Mes)or 2,4,6-triisopropylphenyl (Trip).

In a particularly preferred embodiment, R¹ is methyl.

In a particularly preferred embodiment, R² is phenyl,2,4,6-trimethylphenyl (Mes) or 2,4,6-triisopropylphenyl (Trip).

In the catalysts of the general formula (I), X is an anionic ligand.

In a preferred embodiment, X is hydride, halide, pseudohalide, alkoxide,amide, triflate, phosphate, borate, straight-chain or branchedC₁-C₃₀-alkyl or C₆-C₂₄-aryl, carboxylate, acetate, halogenated acetate,halogenated alkylsulfonate, tosylate or any weakly coordinating anionicligands.

In a more preferred embodiment, X is hydride or halide preferablyfluoride, chloride, bromide or iodide.

In a particularly preferred embodiment, X is chloride.

In the catalysts of the general formula (I), Y¹ and Y² are identical ordifferent and are each a C₁-C₁₀-alkylphosphine ligand,C₃-C₂₀-cycloalkylphosphine ligand, preferably tricyclohexylphosphine(PCy₃), a sulfonated C₁-C₁₀-alkylphosphine ligand, aC₁-C₁₀-alkylphosphinite ligand, a C₁-C₁₀-alkylphosphonite ligand, aC₁-C₁₀-alkyl phosphite ligand, a C₁-C₁₀-alkylarsine ligand, aC₁-C₁₀-alkylamine ligand, a substituted or not substituted pyridineligand, C₁-C₁₀-alkyl sulfoxide ligand, a C₁-C₁₀-alkyloxy ligand or aC₁-C₁₀-alkylamide ligand, each of which may be substituted by a phenylgroup which may in turn be substituted by a halogen, C₁-C₅-alkyl orC₁-C₅-alkoxygroup.

The term “phosphine” includes, for example, P(CF₃)₃, P(isopropyl)₃,P(CHCH₃(CH₂CH₃))₃, P(cyclopentyl)₃, P(cyclohexyl)₃ and P(neopentyl)₃.

The term “phosphinite” includes, for example, cyclohexyldicyclohexylphosphinite and isopropyl diisopropylphosphinite.

The term “phosphite” includes, for example, tricyclohexyl phosphite,tri-tert-butyl phosphite and triisopropyl phosphite.

The term “sulphonate” includes, for example, trifluoromethanesulphonate,tosylate and mesylate.

The term “sulfoxide” includes, for example, (CH₃)₂S(═O) and (C₆H₅)₂S═O.

The term “thioether” includes, for example, CH₃SCH₃, C₆H₅SCH₃,CH₃OCH₂CH₂SCH₃ and tetrahydrothiophene.

Definition of Preferred Catalysts:

A preferred catalyst has the general formula (I) in which

-   R is independently of one another hydrogen, halogen, nitro, methyl,    ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or    tert-butyl, phenyl, or together with the carbon atoms to which they    are bound form a C₆-C₁₀-cycloalkyl or C₆-C₁₀-aryl substituent, alkyl    thiolate, aryl thiolate, B(R³)₂ or B(R³)₃, whereas R³ is alkyl,    aryl, alkoxy or aryloxy or CF₃,-   n is 0 to 4, preferably 0 to 2, more preferably 0 to 1-   R¹ and R² are identical or different and are each methyl, ethyl,    n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl or    neopentyl, cyclohexyl, adamantyl, phenyl, C₁-methanesulphonate,    p-toluenesulphonate, 2,4,6-trimethylphenyl (Mes) or    2,4,6-triisopropylphenyl (Trip),-   X is hydride, halide, pseudohalide, alkoxide, amide, triflate,    phosphate, borate, straight-chain or branched C₁-C₃₀-alkyl or    C₆-C₂₄-aryl, carboxylate, acetate, halogenated acetate, halogenated    alkylsulfonate, tosylate or any weakly coordinating anionic ligands,    and-   Y¹ and Y² are identical or different and are each    C₁-C₁₀-alkylphosphine or C₃-C₂₀-cycloalkylphosphine ligand,    preferably tricyclohexylphosphine (PCy₃), a sulfonated    C₁-C₁₀-alkylphosphine ligand, a C₁-C₁₀-alkylphosphinite ligand, a    C₁-C₁₀-alkylphosphonite ligand, a C₁-C₁₀-alkyl phosphite ligand, a    C₁-C₁₀-alkylarsine ligand, a C₁-C₁₀-alkylamine ligand, a substituted    or not substituted pyridine ligand, a C₁-C₁₀-alkyl sulfoxide ligand,    a C₁-C₁₀-alkyloxy ligand or a C₁-C₁₀-alkylamide ligand, each of    which may be substituted by a phenyl group which may in turn be    substituted by a halogen, C₁-C₅-alkyl or C₁-C₅-alkoxygroup.

A more preferred catalyst has the general formula (I) in which

-   R is independently of one another hydrogen, halogen, methyl, ethyl,    n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl,    phenyl, or together with the carbon atoms to which they are bound    form a C₆-C₁₀-cycloalkyl or C₆-C₁₀-aryl substituent, or CF₃,-   n is 0 to 4, preferably 0 to 2, more preferably 0 to 1-   R¹ and R² are identical or different and are each methyl, ethyl,    n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl or    cyclohexyl, phenyl, 2,4,6-trimethylphenyl (Mes) or    2,4,6-triisopropylphenyl (Trip),-   X is hydride or halide, preferably fluoride, chloride, bromide or    iodide, and-   Y¹ and Y² are identical or different and are each    C₁-C₁₀-alkylphosphine or C₃-C₂₀-cycloalkylphosphine ligand,    preferably tricyclohexylphosphine (PCy₃), a sulfonated    C₁-C₁₀-alkylphosphine ligand, a C₁-C₁₀-alkylphosphinite ligand, a    C₁-C₁₀-alkylphosphonite ligand, a or C₁-C₁₀-alkyl phosphite ligand,    a C₁-C₁₀-alkylarsine ligand, a C₁-C₁₀-alkylamine ligand, a    substituted or not substituted pyridine ligand, a C₁-C₁₀-alkyl    sulfoxide ligand, a C₁-C₁₀-alkyloxy ligand or a C₁-C₁₀-alkylamide    ligand, each of which may be substituted by a phenyl group which may    in turn be substituted by a halogen, C₁-C₅-alkyl or    C₁-C₅-alkoxygroup.

An even more preferred catalyst has the general formula (I) in which

-   R is independently of one another hydrogen, methyl or CF₃,-   n is 0 to 4, preferably 0 to 2, more preferably 0 to 1-   R¹ is methyl,-   R² is phenyl, 2,4,6-trimethylphenyl (Mes) or    2,4,6-triisopropylphenyl (Trip),-   X is chloride, and-   Y¹ and Y² are each tricyclohexylphosphine (PCy₃).

Synthesis of Catalysts:

In order to prepare the catalysts according to general formula (I) andall preferred, more preferred, even more preferred and particularlypreferred catalysts, a person skilled in the art can use multistepprocedures as outlined and exemplified in the experimental section ofthis application for various catalysts and can apply, generalize andmodify to the extent necessary such described procedures to preparecatalysts falling under general formula (I). The preparation methodstypically include schlenk or glovebox techniques. The characterizationof the catalysts, substrates and compounds e.g. by ¹H-, ¹³C-, ¹⁹F-,³¹P-, or, or ¹¹B-NMR, elemental analysis, and ESI-MS as outlined in theexperimental section of this application are routine to a person skilledin the art of synthetic chemistry.

Typically, the catalyst according to formula (I) can be prepared byadding a solvent such as benzene or toluene to a mixture of substitutedsilver(I) triazolylidene and a ruthenium-complex such asRuHCl(H₂)(PCy₃)₂ or RuHCl(PPh₃)₃, which can be synthesized according toa modified literature procedure (M. Viciano, M. Feliz, R. Corberan, J.A. Mata, E. Clot and E. Pens, Organometallics, 2007, 26, 5304-5314.).The reaction mixture is than typically stirred at room temperature forabout 40 to 50 hours. The catalyst can be typically purified byfiltration, decantation or crystallization.

The present invention further relates to a process of hydrogenatingsubstrates possessing at least one carbon-carbon double bond comprisingsubjecting said substrate to a hydrogenation reaction in the presence ofa catalyst according to general formula (I).

Substrates to be Hydrogenated:

The process of the present invention is broadly applicable to thehydrogenation of a variety of substrates, including terminal olefins,internal olefins, cyclic olefins, conjugated olefins, and any furtherolefins having at least one carbon-carbon double bond and additionallyat least one further polar unsaturated double or triple bond. Theprocess is also applicable to the hydrogenation of polymers havingcarbon-carbon double bonds. Such polymers may represent homo-, co- orterpolymers.

As a terminal olefin or alkene, it is possible to hydrogenate ahydrocarbon compound with a terminal unsaturated carbon-carbon doublebond having the general formula C_(n)H_(2n). The terminal olefin can bea straight-chain or a branched hydrocarbon compound of any length,preferably 1-hexene.

As an internal olefin or alkene, it is possible to hydrogenate ahydrocarbon compound with an internal unsaturated carbon-carbon doublebond having the general formula C_(n)H_(2n). The internal olefin can bea straight-chain or a branched hydrocarbon of any length, and may be2-hexene.

As a cyclic olefin or cycloalkene, it is possible to hydrogenate ahydrocarbon compound with a cyclic unsaturated carbon-carbon double bondhaving the general formula C_(n)H_(2n-2). The cyclic olefin can be aring of any size, and may be cyclohexene.

As a conjugated olefin or dialkene, it is possible to hydrogenate ahydrocarbon compound with conjugated carbon-carbon unsaturated doublebonds. The conjugation can be a straight-chain or a branched hydrocarbonof any length, preferably styrene.

As an olefin, it is also possible to selectively hydrogenate ahydrocarbon compound with at least one unsaturated carbon-carbon doublebond and at least one other unsaturated polar double or triple bond.Such unsaturated polar bonds are surprisingly left unaltered. Thecarbon-carbon double bond in such olefins can be of any nature includingterminal, internal, cyclic and conjugated ones. The additionalunsaturated polar bond can be of any nature with preference given tocarbon-nitrogen, carbon-phosphorus, carbon-oxygen, and carbon-sulfurunsaturated polar bonds.

Polymers having carbon-carbon double bonds may also be subjected to theinventive process. Such polymers preferably comprise repeating unitsbased on at least one conjugated diene monomer.

The conjugated diene can be of any nature. In one embodimentC₄-C₆-conjugated dienes are used. Preference is given to 1,3-butadiene,isoprene, 1-methylbutadiene, 2,3-dimethylbutadiene, piperylene,chloroprene, or mixtures thereof. More preference is given to1,3-butadiene, isoprene or mixtures thereof. Particular preference isgiven to 1,3-butadiene.

In a further embodiment polymers having carbon-carbon double bonds maybe subjected to the inventive process which comprise repeating units ofnot only at least one conjugated diene as monomer (a) but additionallyat least one further copolymerizable monomer (b).

Examples of suitable monomers (b) are olefins, such as ethylene orpropylene.

Further examples of suitable monomers (b) are vinylaromatic monomers,such as styrene, α-methyl styrene, o-chlorostyrene or vinyltoluenes,vinylesters of aliphatic or branched C₁-C₁₈-monocarboxylic acids, suchas vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate,vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl decanoate, vinyl laurateand vinyl stearate.

A preferred polymer to be used in the present invention is a copolymerof 1,3-butadiene and styrene or α-methylstyrene. Said copolymers mayhave a random or block type structure.

Further examples of suitable monomers (b) are esters of ethylenicallyunsaturated monocarboxylic acids or mono- or diesters of dicarboxylicacids with generally C₁-C₁₂-alkanols, e.g. esters of acrylic acid,methacrylic acid, maleic acid, fumaric acid and itaconic acid with e.g.methanol, ethanol, n-propanol, isopropanol, 1-butanol, 2-butanol,isobutanol, tert.-butanol, n-hexanol, 2-ethylhexanol, orC₅-C₁₀-cycloalkanols, such as cyclopentanol or cyclohexanol, and ofthese preferably the esters of acrylic and/or methacrylic acid, examplesbeing methyl methacrylate, n-butyl methacrylate, tert-butylmethacrylate, n-butyl acrylate, tert-butyl acrylate, and 2-ethylhexylacrylate.

The inventive process may be further used to hydrogenate so-callednitrile rubbers. Nitrile rubbers (“NBR”) represent copolymers orterpolymers comprising repeating units of at least one conjugated dieneand at least one α,β-unsaturated nitrile monomer, or copolymers orterpolymers comprising repeating units of at least one conjugated dieneand at least one α,β-unsaturated nitrile monomer and one or more furthercopolymerizable monomers.

The conjugated diene in such nitrile rubbers can be of any nature.Preference is given to using C₄-C₆-conjugated dienes. Particularpreference is given to 1,3-butadiene, isoprene, 2,3-dimethylbutadiene,piperylene or mixtures thereof. In particular, use is preferably made of1,3-butadiene or isoprene or mixtures thereof. Very particularpreference is given to 1,3-butadiene.

As α,β-unsaturated nitrile monomer, it is possible to use any knownα,β-unsaturated nitrile, with preference being given toC₃-C₅-α,β-unsaturated nitriles such as acrylonitrile, methacrylonitrile,ethacrylonitrile or mixtures thereof. Particularly preference is givento acrylonitrile.

A particularly preferred nitrile rubber to be subjected to hydrogenationaccording to the invention is thus a copolymer of acrylonitrile and1,3-butadiene.

In addition to the conjugated diene and the α,β-unsaturated nitrile, itis possible to use one or more further copolymerizable monomers known tothose skilled in the art, e.g. termonomers containing carboxyl groups,like α,β-unsaturated monocarboxylic acids, their esters or amides,α,β-unsaturated dicarboxylic acids, their monoesters or diesters, ortheir corresponding anhydrides or amides.

As α,β-unsaturated monocarboxylic acids it is possible to use acrylicacid and methacrylic acid.

It is also possible to employ esters of the α,β-unsaturatedmonocarboxylic acids, preferably their alkyl esters and alkoxyalkylesters. Preference is given to the alkyl esters, especially C₁-C₁₈-alkylesters, of the α,β-unsaturated monocarboxylic acids. Particularpreference is given to alkyl esters, especially C₁-C₁₈-alkyl esters, ofacrylic acid or of methacrylic acid, more particularly methyl acrylate,ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate,2-ethylhexyl acrylate, n-dodecyl acrylate, methyl methacrylate, ethylmethacrylates, butyl methacrylate and 2-ethylhexyl methacrylate. Alsopreferred are alkoxyalkyl esters of the α,β-unsaturated monocarboxylicacids, more preferably alkoxyalkyl esters of acrylic acid or ofmethacrylic acid, more particular C₂-C₁₂-alkoxyalkyl esters of acrylicacid or of methacrylic acid, very preferably methoxymethyl acrylate,methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and methoxyethyl(meth)acrylate. Use may also be made of mixtures of alkyl esters, suchas those mentioned above, for example, with alkoxyalkyl esters, in theform of those mentioned above, for example. Use may also be made ofcyanoalkyl acrylate and cyanoalkyl methacrylates in which the C atomnumber of the cyanoalkyl group is 2-12, preferably α-cyanoethylacrylate, β-cyanoethyl acrylate and cyanobutyl methacrylate. Use mayalso be made of hydroxyalkyl acrylates and hydroxyalkyl methacrylate inwhich the C atom number of the hydroxyalkyl groups is 1-12, preferably2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 3-hydroxypropylacrylate; use may also be made of fluorine-substitutedbenzyl-group-containing acrylates or methacrylates, preferablyfluorobenzyl acrylate, and fluorobenzyl methacrylate. Use may also bemade of acrylates and methacrylates containing fluoroalkyl groups,preferably trifluoroethyl acrylate and tetrafluoropropyl methacrylate.Use may also be made of α,β-unsaturated carboxylic esters containingamino groups, such as dimethylaminomethyl acrylate and diethylaminoethylacrylate.

As copolymerizable monomers it is possible, furthermore, to useα,β-unsaturated dicarboxylic acids, preferably maleic acid, fumaricacid, crotonic acid, itaconic acid, citraconic acid and mesaconic acid.

Use may be made, furthermore, of α,β-unsaturated dicarboxylicanhydrides, preferably maleic anhydride, itaconic anhydride, citraconicanhydride and mesaconic anhydride.

It is possible, furthermore, to use monoesters or diesters ofα,β-unsaturated dicarboxylic acids.

These α,β-unsaturated dicarboxylic monoesters or diesters may be, forexample, alkyl esters, preferably C₁-C₁₀-alkyl, more particularly ethyl,n-propyl, iso-propyl, n-butyl, tert-butyl, n-pentyl or n-hexyl esters,alkoxyalkyl esters, preferably C₂-C₁₂-alkoxyalkyl, more preferablyC₃-C₈-alkoxyalkyl, hydroxyalkyl, preferably C₁-C₁₂-hydroxyalkyl, morepreferably C₂-C₈-hydroxyalkyl, cycloalkyl esters, preferablyC₅-C₁₂-cycloalkyl, more preferably C₈-C₁₂-cycloalkyl, alkylcycloalkylesters, preferably C₈-C₁₂-alkylcycloalkyl, more preferablyC₇-C₁₀-alkylcycloalkyl, aryl esters, preferably C₈-C₁₄-aryl esters,these esters being monoesters or diesters, and it also being possible,in the case of the diesters, for the esters to be mixed esters.

Particularly preferred alkyl esters of α,β-unsaturated monocarboxylicacids are methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate,2-propylheptyl acrylate and lauryl (meth)acrylate. More particularly,n-butyl acrylate is used.

Particularly preferred alkoxyalkyl esters of the α,β-unsaturatedmonocarboxylic acids are methoxyethyl (meth)acrylate, ethoxyethyl(meth)acrylate and methoxyethyl (meth)acrylate. More particularly,methoxyethyl acrylate is used.

Particularly preferred hydroxyalkyl esters of the α,β-unsaturatedmonocarboxylic acids are hydroxyethyl (meth)acrylate, hydroxypropyl(meth)acrylate and hydroxybutyl (meth)acrylate.

Other esters of the α,β-unsaturated monocarboxylic acids that are usedare additionally, for example, polyethylene glycol (meth)acrylate,polypropylene glycol (meth)acrylate, glycidyl (meth)acrylate, epoxy(meth)acrylate, N-(2-hydroxyethyl)acrylamides,N-(2-hydroxy-methyl)acrylamides and urethane (meth)acrylate.

Examples of α,β-Unsaturated Dicarboxylic Monoesters Encompass

-   -   maleic acid monoalkyl esters, preferably monomethyl maleate,        monoethyl maleate, monopropyl maleate and mono-n-butyl maleate;    -   maleic acid monocycloalkyl esters, preferably monocyclopentyl        maleate, monocyclohexyl maleate and monocycloheptyl maleate;    -   maleic acid monoalkyl cycloalkyl esters, preferably monomethyl        cyclopentyl maleate and monoethyl cyclohexyl maleate;    -   maleic acid monoaryl esters, preferably monophenyl maleate;    -   maleic acid monobenzyl esters, preferably monobenzyl maleate;    -   fumaric acid monoalkyl esters, preferably monomethyl fumarate,        monoethyl fumarate, monopropyl fumarate and mono-n-butyl        fumarate;    -   fumaric acid monocycloalkyl esters, preferably monocyclopentyl        fumarate, monocyclohexyl fumarate and monocycloheptyl fumarate;    -   fumaric acid monoalkyl cycloalkyl esters, preferably monomethyl        cyclopentyl fumarate and monoethyl cyclohexyl fumarate;    -   fumaric acid monoaryl esters, preferably monophenyl fumarate;    -   fumaric acid monobenzyl esters, preferably monobenzyl fumarate;    -   citraconic acid monoalkyl esters, preferably monomethyl        citraconate, monoethyl citraconate, monopropyl citraconate and        mono-n-butyl citraconate;    -   citraconic acid monocycloalkyl esters, preferably        monocyclopentyl citraconate, monocyclohexyl citraconate and        monocycloheptyl citraconate;    -   citraconic acid monoalkyl cycloalkyl esters, preferably        monomethyl cyclopentyl citraconate and monoethyl cyclohexyl        citraconate;    -   citraconic acid monoaryl esters, preferably monophenyl        citraconate;    -   citraconic acid monobenzyl esters, preferably monobenzyl        citraconate;    -   itaconic acid monoalkyl esters, preferably monomethyl itaconate,        monoethyl itaconate, monopropyl itaconate and mono-n-butyl        itaconate;    -   itaconic acid monocycloalkyl esters, preferably monocyclopentyl        itaconate, monocyclohexyl itaconate and monocycloheptyl        itaconate;    -   itaconic acid monoalkyl cycloalkyl esters, preferably monomethyl        cyclopentyl itaconate and monoethyl cyclohexyl itaconate;    -   itaconic acid monoaryl esters, preferably monophenyl itaconate;    -   itaconic acid monobenzyl esters, preferably monobenzyl        itaconate;    -   mesaconic acid monoalkyl esters, preferably mesaconic acid        monoethyl esters;

As α,β-unsaturated dicarboxylic diesters it is possible to use theanalogous diesters based on the abovementioned monoester groups, and theester groups may also be chemically different groups.

Preferably the substrate to be hydrogenated is a nitrile rubbercomprising repeating units of at least one conjugated diene and at leastone α,β-unsaturated nitrile monomer, or a nitrile rubber comprising atleast one conjugated diene and at least one α,β-unsaturated nitrilemonomer and one or more further copolymerizable monomers, preferably anitrile rubber comprising repeating units of at least one conjugateddiene selected from the group consisting of 1,3-butadiene, isoprene,2,3-dimethylbutadiene, piperylene and mixtures thereof, at least oneα,β-unsaturated nitrile selected from the group consisting ofacrylonitrile, methacrylonitrile, ethacrylonitrile and mixtures thereof,and of no or one or more further copolymerizable monomers selected fromthe group consisting of α,β-unsaturated monocarboxylic, dicarboxylicacids, their esters or amides.

The proportions of conjugated diene and α,β-unsaturated nitrile monomerin the NBR polymers to be used can vary within wide ranges. Theproportion of the conjugated diene or the sum of conjugated dienes isusually in the range from 40% to 90% by weight, preferably in the rangefrom 50% to 85% by weight, based on the total polymer. The proportion ofthe α,β-unsaturated nitrile or the sum of the α,β-unsaturated nitrilesis usually from 10% to 60% by weight, preferably from 15% to 50% byweight, based on the total polymer. The proportions of the monomers ineach case add up to 100% by weight. The additional monomers can bepresent in amounts of from 0% to 40% by weight, preferably from 0.1% to40% by weight, particularly preferably from 1% to 30% by weight, basedon the total polymer. In this case, corresponding proportions of theconjugated diene or dienes and/or the α,β-unsaturated nitrile ornitriles are replaced by the proportions of the additional monomers,with the proportions of all monomers in each case adding up to 100% byweight.

The preparation of such nitrile rubbers by polymerization of theabovementioned monomers is adequately known to those skilled in the artand is comprehensively described in the literature (e.g. Houben-Weyl,Methoden der Organischen Chemie Bd.14/1, 30 Georg Thieme VerlagStuttgart 1961; Rompp Lexikon der Chemie, Band 2, 10. Auflage 1997; P.A. Lovell, M. S. El-Aasser, Emulsion Polymerization and EmulsionPolymers, John Wiley & Sons, ISBN: 0471 967467; H. Gerrens, Fortschr.Hochpolym. Forsch. 1, 234 (1959)).

Nitrile rubbers which can be used for the purposes of the invention arealso commercially available, e.g. as products marketed under thetrademarks Perbunan® and Krynac® by Lanxess Deutschland GmbH.

The nitrile rubbers which can be used for the hydrogenation have aMooney viscosity (ML 1+4 at 100° C.) in the range from 30 to 70,preferably from 30 to 50. This corresponds to a weight average molecularweight M_(w) in the range from 150,000 to 500,000, preferably in therange from 180,000 to 400,000. The nitrile rubbers used typically have apolydispersity PDI=M_(w)/M_(n) (M_(n) is the number average molecularweight) in the range of 2.0-6.0 and preferably in the range 2.0-4.0.

The determination of the Mooney viscosity is carried out in accordancewith ASTM standard D 1646.

Hydrogenated nitrile rubbers obtained pursuant to this invention canhave a Mooney viscosity (ML 1+4 at 100° C.) in the range of greater than0 up to 150, typically the Mooney viscosity lies in the range of from 5to 150, preferably of from 10 to 120, more preferably of from 30 to 110,even more preferably of from 35 to 100, and particularly preferably offrom 50 to 100 and most preferably of from 60 to 90.

They typically have a polydispersity PDI=M_(w)/M_(n), where M_(w) is theweight average molecular weight and M_(n) is the number averagemolecular weight, in the range of 1.5 to 6 and preferably in the rangeof 1.8 to 4.

Hydrogenation Conditions:

The process of the present invention is generally carried out at atemperature in the range from 0° C. to 200° C., preferably in the rangefrom 15° C. to 150° C. This means that the process may be carried out atmild conditions. In case low molecular weight olefins like terminalolefins, internal olefins, cyclic olefins, conjugated olefins, or anyother olefins having at least one carbon-carbon double bond andadditionally at least one further polar unsaturated double bond aresubjected to hydrogenation, the temperature typically lies in the rangefrom 20° C. to 100° C. In case polymers with double bonds in the polymerbackbone are used as substrates the hydrogenation temperature typicallylies in a range from 40° C. to 200° C., preferably in the range from 70°C. to 150° C.

The hydrogenation process of the present invention is preferably carriedout with hydrogen gas at a pressure from 0.1 MPa to 20 MPa, preferablyat a pressure from 1 MPa to 16 MPa. In one embodiment of the presentprocess said hydrogen gas is essentially pure.

Preferably the hydrogenation process is carried out at a temperature inthe range from 0° C. to 200° C. with hydrogen gas at a pressure from 0.1MPa to 20 MPa, preferably at a temperature in the range from 15° C. to150° C. with hydrogen gas at a pressure from 1 MPa to 16 MPa.

The amount of catalyst according to general formula (I) can vary in abroad range. Typically the catalyst according to general formula (I) isused in a molar ratio from (0.01-0.20):1, preferably from (0.01-0.05):1based on the substrate to be hydrogenated.

In the hydrogenation of rubber polymers the amount of catalyst accordingto formula (I) may also vary in a broad range. The amount of catalyst isthen calculated on a weight base ratio in “phr” (parts per hundredrubber). Typically 0.005 phr to 2.5 phr catalyst are used based on therubber. Preferably 0.01 phr to 2 phr and more preferably 0.025 phr to 2phr catalyst are used based on the rubber.

The hydrogenation can be carried out in a suitable solvent which doesnot deactivate the catalyst used and also does not adversely affect thereaction in any other way. Preferred solvents include but are notrestricted to methanol, chlorobenzene, bromobenzene, dichloromethane,benzene, toluene, methyl ethyl ketone, acetone, tetrahydrofuran,tetrahydropyran, dioxane and cyclohexane. The particularly preferredsolvent is chlorobenzene. In some cases, when the substrate to behydrogenated itself can function as solvent, e.g. in the case of1-hexene, the addition of a further additional solvent can also beomitted.

According to the present invention the catalyst can be introduced intothe polymer by any possible means, such as e.g. mechanical mixing,preferably by using a procedure which can result in a homogeneousdistribution of the catalyst and polymer.

In one embodiment of the present invention the catalyst according toformula (I) is contacted with the substrate to be hydrogenated by addingthe catalyst or catalyst solution to a substrate solution and mixinguntil an efficient distribution and dissolution of the catalyst hastaken place.

The present process can be performed in the presence or absence of anyfurther co-catalyst or other additives. It is not necessary to add suchfurther co-catalyst or other additives. This applies in particular toco-catalysts which are typically used e.g. in combination with otherhydrogenation catalysts known from prior art like the Wilkinson'scatalyst. In one embodiment of the present invention the process isconducted in the presence or absence of co-catalysts having the formulaR¹ _(m)Z, wherein R¹ are identical or different and are each aC₁-C₈-alkyl group, a C₄-C₈-cycloalkyl group, a C₆-C₁₅-aryl group or aC₇-C₁₅-aralkyl group, Z is phosphorus, arsenic, sulphur or a sulphoxidegroup S═O, preferably phosphorus, and m is 2 or 3, preferably 3. In afurther embodiment the present process is conducted in the presence orabsence of triphenylphosphine.

The hydrogenation process of the present invention can be undertaken ina suitable reactor equipped with temperature regulating and agitatingmeans. It is possible to perform the process either batch-wise orcontinuously.

During the course of the hydrogenation reaction of the presentinvention, the hydrogen is added to the reactor. The reaction time istypically from about one quarter of an hour to about 100 hours,depending on operational conditions. As the novel catalysts are robust,it is not necessary to use a special gas dryer to dry the hydrogen.

According to the present invention, when the hydrogenation reaction iscomplete, to the extent desired, the reaction vessel can be cooled, ifapplicable, and vented and the hydrogenated substrate can be isolated byconventional methods well known to any artisan.

During the process according to the invention it may happen that ahydrogenation reaction and a metathesis reaction occur simultaneously.In case polymeric substrates, and in particular nitrile rubbers, areused as substrates in the process according to the invention, suchmetathesis reaction results in a decrease of the molecular weight of thesubstrate.

The novel ruthenium-based triazole carbene complexes can be used ascatalysts for the hydrogenation of unsaturated compounds comprisingcarbon-carbon double bonds, preferably nitrile rubber.

Such complex catalysts are inexpensive, thermally robust, gel formationinhibiting and olefin selective.

EXAMPLES

In the following “PPh₃” is used as an abbreviation oftriphenylphosphine, “Ph” means in each case phenyl, “Mes” represents ineach case 2,4,6-trimethylphenyl, “Trip” is used as an abbreviation of2,4,6-triisopropylphenyl, “iPr₃” is used as an abbreviation oftriisopropyl and “PCy₃” is used as an abbreviation oftricyclohexylphosphine.

General Procedures:

Manipulations were done using standard Schlenk and glovebox techniques(O₂ level <0.1 ppm; N₂ as inert gas), unless noted differently.Solvents, namely CH₂Cl₂, Et₂O, THF, toluene, and hexane, were used indried form and stored under N₂. RuHCl(PPh₃)₃ and RuHCl(H₂)(PCy₃)₂ wereprepared according to a modified literature procedure (M. Viciano, M.Feliz, R. Corberan, J. A. Mata, E. Clot and E. Pens, Organometallics,2007, 26, 5304-5314.).

A Synthesis of Ligands and Catalysts

Synthesis of 1.

Benzene (10 mL) was added to a mixture of[(C₆H₂iPr₃)CH₂C₂N₂(NMe)Ph)₂Ag][AgCl₂] (0.261 g, 0.25 mmol) andRuHCl(H₂)(PCy₃)₂ (0.350 g, 0.50 mmol). The reaction mixture was stirredat room temperature for 48 hours resulting in a red solution with brownprecipitate. The brown solid was filtered off. All volatiles wereremoved from the red solution resulting in a red solid which was washedwith hexane (3×10 mL). The solid was dried under high vacuum to give 1as pure product (0.351 g). The hexane phase was allowed to rest for 48hours during which time red crystals formed (0.058 g) as pure product 1.The solids were combined and dried thoroughly to give 1 (0.409 g, 76%).

Compound 1:

¹H-NMR (CD₂Cl₂): δ 0.92-2.16 (m, 84H, PCy₃ and CH₃ of iPr), 2.97 (sept,J=6.9 Hz, 1H, CH of iPr), 3.07 (sept, J=6.9 Hz, 2H, CH of iPr), 4.11 (s,3H, N—CH₃), 5.58 (s, 2H, CH₂), 6.51 (t, J=7.7 Hz, 1H, C₆H₄), 6.60 (t,J=7.2 Hz, 1H, C₆H₄), 7.08 (d, J=7.5 Hz, 1H, C₆H₄), 7.18 (s, 2H, C₆H₂),8.25 (d, J=8.0 Hz, 1H, C₆H₄).

¹³C-NMR (CD₂Cl₂): δ 24.12, 26.99, 28.05, 28.33, 28.59, 30.69, 30.97,31.53, 34.70, 37.09, 38.20 (PCy₃, CH and CH₃ of iPr), 49.28 (N—CH₃),66.06 (CH₂), 117.52, 118.91, 122.03, 122.34, 125.50, 139.91, 143.65,149.44, 150.04, 154.62 (Ar—C), 181.59 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 24.49.

Anal. Calcd for C₆₁H₉₈ClN₃P₂Ru (1071.92): C, 68.35; H, 9.22; N, 3.92.

Found: C, 68.22; H, 9.21; N, 3.87.

Synthesis of 2 and 3.

Benzene (10 mL) was added to a mixture of[(C₆H₆)CH₂C₂N₂(NMe)Ph)₂Ag][AgCl₂] (0.197 g, 0.25 mmol) andRuHCl(H₂)(PCy₃)₂ (0.350 g, 0.50 mmol). The reaction mixture was stirredat room temperature for 48 hours resulting in a red solution with brownprecipitate. The brown solid was filtered off. The red solution wasconcentrated to ca. 2-3 mL and added dropwise to hexane (15 mL) whilestirring vigorously. This resulted in a red solution with orangeprecipitate. The solid was filtered off and dried under high vacuum togive 2 (0.291 g, ca. 60%) (compound 2 contains impurities and could notbe isolated in pure form). The red solution was allowed to rest 18 hoursat room temperature resulting in an orange semicrystalline precipitateand red solution. The red solution was left at −35° C. for 48 hoursresulting in red crystals. The crystals were dried to give pure 3 (0.038g, 8%).

Synthesis of 4 and 5.

Benzene (10 mL) was added to a mixture of[(C₆H₂Me₃)CH₂C₂N₂(NMe)Ph)₂Ag][AgCl₂] (0.230 g, 0.25 mmol) andRuHCl(H₂)(PCy₃)₂ (0.350 g, 0.50 mmol). The reaction mixture was stirredat room temperature for 48 hours resulting in a red solution with brownprecipitate. The brown solid was filtered off. The red solution wasconcentrated to ca. 2-3 mL and added dropwise to hexane (15 mL) whilestirring vigorously. This resulted in a red solution with orangeprecipitate. The solid was filtered off and dried under high vacuum togive 4 (0.281 g, 56%) as crude product. Crystallization from toluenegave pure 4 (0.202 g, 40%) as red crystals. The red solution was allowedto rest 18 hours at room temperature resulting in an orangesemicrystalline precipitate and red solution. The red solution was leftat −35° C. for 48 hours resulting in red crystals. The crystals weredried to give pure 5 (0.038 g, 8%).

Compound 4:

¹H-NMR (CD₂Cl₂): δ 1.08-2.23 (m, 66H, PCy₃), 2.30 (s, 3H, CH₃), 2.41 (s,6H, CH₃), 4.23 (s, 3H, N—CH₃), 5.96 (s, 2H, CH₂), 6.98 (m, 1H, C₆H₄),7.52-7.79 (m, 4H, C₆H₂ and C₆H₄), 9.01 (m, 1H, C₆H₄).

¹³C-NMR (CD₂Cl₂): δ 20.15, 21.18, 24.35, 27.14, 28.28, 29.42, 30.24,30.64, 32.32, 33.22, 38.19, 39.26 (PCy₃ and CH₃), 49.04 (N—CH₃), 62.86(CH₂), 122.37, 125.36, 128.64, 129.35, 129.81, 130.04, 132.28, 139.16,140.65, 143.54 (Ar—C), 178.51 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 23.96.

Anal. Calcd for C₅₅H₈₆ClN₃P₂Ru (987.76): C, 66.88; H, 8.78; N, 4.25.

Found: C, 66.81; H, 8.91; N, 4.26.

Synthesis of 6 and 7.

Benzene (10 mL) was added to a mixture of[((C₆H₂Me₃)CH₂C₂N₂(NMe)(C₆H₄Me))₂Ag][AgCl₂] (0.216 g, 0.26 mmol) andRuHCl(H₂)(PCy₃)₂ (0.350 g, 0.50 mmol). The reaction mixture was stirredat room temperature for 48 hours resulting in a red solution with brownprecipitate. The brown solid was filtered off. The red solution wasconcentrated to ca. 2-3 mL and added dropwise to hexane (15 mL) whilestirring vigorously. This resulted in a red solution with orange-redprecipitate. The solid was filtered off and dried under high vacuum togive 6 as crude product. The crude product was dissolved in toluene andcrystallization gave red crystals as pure 6 (0.213 g, 42%). The redsolution was allowed to rest 48 hours at room temperature resulting inred crystals. The crystals were dried and ¹H-NMR measurement suggestedthat the red crystals were a mixture of 6 and 7. Compound 7 could not beisolated in pure.

Compound 6:

¹H-NMR (CD₂Cl₂): δ 0.89-2.05 (m, 66H, PCy₃), 2.24 (s, 3H, CH₃), 4.17 (s,3H, N—CH₃), 5.81 (s, 2H, CH₂), 6.48 (d, J=7.6 Hz, 1H, C₆H₃), 7.06 (d,J=7.6 Hz, 1H, C₆H₃), 7.31-7.42 (m, 5H, C₆H₅), 7.96 (s, 1H, C₆H₃).

¹³C-NMR (CD₂Cl₂): δ 21.78, 22.75, 27.08, 28.44, 30.31, 30.44, 30.63,33.28, 34.54, 36.84, 37.12 (PCy₃, CH₃ and N—CH₃), 56.20 (CH₂), 118.82,118.94, 127.84, 127.98, 128.69, 132.61, 136.51, 137.11, 143.38, 154.31(Ar—C), 183.11, 183.96 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 24.17.

Anal. Calcd for C₅₃H₈₂ClN₃P₂Ru (959.71): C, 66.33; H, 8.61; N, 4.38.

Found: C, 66.25; H, 8.56; N, 4.42.

Synthesis of 8 and 9.

Benzene (10 mL) was added to a mixture of[((C₆H₂Me₃)CH₂C₂N₂(NMe)(C₆H₄CF₃))₂Ag][AgCl₂] (0.244 g, 0.26 mmol) andRuHCl(H₂)(PCy₃)₂ (0.350 g, 0.50 mmol). The reaction mixture was stirredat room temperature for 48 hours resulting in a red solution with brownprecipitate. The brown solid was filtered off. The red solution wasconcentrated to ca. 2-3 mL and added dropwise to hexane (15 mL) whilestirring vigorously. This resulted in a red solution with orange-redprecipitate. The solid was filtered off and dried under high vacuum togive 8 as crude product. The crude product was dissolved in toluene andcrystallization gave red crystals as pure 8 (0.193 g, 38%). The redsolution was allowed to rest 48 hours at room temperature resulting inred crystals. The crystals were dried and ¹H-NMR measurement suggestedthat the red crystals were a mixture of 8 and 9. Compound 9 could not beisolated in pure form.

Compound 8:

¹H-NMR (CD₂Cl₂): δ 0.83-2.04 (m, 66H, PCy₃), 4.25 (s, 3H, N—CH₃), 5.85(s, 2H, CH₂), 6.91 (d, J=7.5 Hz, 1H, C₆H₃), 7.23 (d, J=7.5 Hz, 1H,C₆H₃), 7.31-7.44 (m, 5H, C₆H₅), 8.43 (s, 1H, C₆H₃).

¹³C-NMR (CD₂Cl₂): δ 26.98, 28.28, 28.31, 28.36, 30.48, 30.53, 36.70,36.76, 36.82, 37.54 (PCy₃ and N—CH₃), 56.37 (CH₂), 114.08, 118.42,127.95, 128.81, 129.67, 130.34, 136.04, 138.53, 143.40, 153.15 (Ar—C andCF₃), 184.81, 186.88 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 23.58.

Anal. Calcd for C₅₃H₇₉ClN₃P₂Ru (1013.68): C, 62.80; H, 7.86; N, 4.15.

Found: C, 62.87; H, 7.83; N, 4.18.

Synthesis of 10.

Toluene (30 mL) was added to a mixture of[(C₆H₂iPr₃)CH₂C₂N₂(NMe)Ph)₂Ag][AgCl₂] (0.520 g, 0.50 mmol) andRuHCl(PPh₃)₃ (0.926 g, 1.00 mmol). The reaction mixture was stirred atroom temperature for 40 hours resulting in a dark red solution withbrown precipitate. The precipitate was filtered off and the solution wasconcentrated to ca. one fourth to its original volume. The concentratedsolution was added dropwise to well stirred hexanes (30 mL) resulting ina red precipitate with pale red solution. The liquid was syringed offand the solid was washed with hexanes (3×10 mL). Pure product as darkred crystals were deposited from the pale red solution on standing. Thered solid was dried to give crude product. The crude product wasdissolved in toluene and crystallization gave second batch of dark redcrystals as pure 10 (0.383 g, 37%). Occasionally colorless crystals ofAgCl(PPh₃) were also crystallized out and separated from the dark redcrystals mechanically.

Compound 10:

¹H-NMR (CD₂Cl₂): δ 0.93 (d, J=6.3 Hz, 12H, CH₃ of iPr), 1.26 (d, J=6.5Hz, 6H, CH₃ of iPr), 2.28 (sept, J=6.3 Hz, 1H, CH of iPr), 2.89 (sept,J=6.3 Hz, 2H, CH of iPr), 3.30 (s, 3H, Me), 5.22 (s, 2H, CH₂), 6.17 (d,J=8.6 Hz, 1H, Ar—H), 6.40-6.45 (m, 2H, Ar—H), 7.01 (s, 2H, Ar—H),7.05-7.42 (m, 30H, PPh₃), 7.91 (d, J=8.6 Hz, 1H, Ar—H).

¹³C-NMR (CD₂Cl₂): δ 24.04 (CH₃ of iPr), 24.98 (CH of iPr), 30.30 (CH₃ ofiPr), 34.60 (CH of Pr), 36.49 (N—CH₃), 48.98 (CH₂), 118.75, 120.46,121.85, 122.94, 124.38, 127.66, 128.70, 140.07, 149.56, 149.91, 154.64(Ar—C), 174.27, 175.45 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 39.95.

Anal. Calcd for C₆₁H₆₂ClN₃P₂Ru (1035.64): C, 70.74; H, 6.03; N, 4.06.

Found: C, 71.01; H, 5.99; N, 4.09.

Synthesis of 11 and 12.

Toluene (30 mL) was added to a mixture of[(O₆H₅)CH₂C₂N₂(NMe)Ph)₂Ag][AgCl₂] (0.396 g, 0.50 mmol) and RuHCl(PPh₃)₃(0.926 g, 1.00 mmol). The reaction mixture was stirred at roomtemperature for 40 hours resulting in a dark red solution with brownprecipitate. The precipitate was filtered off and the solution wasconcentrated to ca. one fourth to its original volume. The concentratedsolution was added dropwise to well stirred hexanes (30 mL) resulting ina red-orange precipitate with pale red solution. The red solution wassyringed off and dark red crystals were obtained on standing for 2 days.The crystals were dried under high vacuum to give pure 12 (0.046 g, 5%).The red-orange solid was washed with hexanes (3×10 mL) and dried to givecrude product 11. The crude product was dissolved in CH₂Cl₂ (3 mL) andslow diffusion of Et₂O over 10 days gave dark red crystals as pure 11(0.191 g, 21%).

Compound 11:

¹H-NMR (CD₂Cl₂): δ 3.34 (s, 3H, Me), 4.86 (s, 2H, CH₂), 6.29-6.36 (m,1H, Ar—H), 6.41-6.49 (m, 2H, Ar—H), 6.80 (d, J=7.6 Hz, 2H, Ar—H),6.95-7.03 (m, 3H, Ar—H), 7.09-7.45 (m, 30H, PPh₃), 8.08 (d, J=7.5 Hz,1H, Ar—H).

¹³C-NMR (CD₂Cl₂): δ 36.59 (N—CH₃), 55.99 (CH₂), 118.83, 120.08, 122.96,124.38, 127.73, 128.70, 129.35, 134.48, 134.79, 135.09, 136.01, 139.77,141.09, 153.53 (Ar—C), 173.39, 180.64 (Ru—C).

³¹P-NMR (CD₂Cl₂): δ 37.70.

Anal. Calcd for C₅₂H₄₄ClN₃P₂Ru (909.40): C, 68.68; H, 4.88; N, 4.62.

Found: C, 68.73; H, 4.85; N, 4.60.

B.1 Hydrogenation of NBR

C₆H₅Cl was distilled over P₂O₅. H₂ was purified by passing through aMatheson gas drier model 450B.

In Series 1 and 2 commercially available Perbunan® T 3435 was used asnitrile rubber:

-   Perbunan® T 3435: 34 wt % ACN; Mooney viscosity (ML 1+4 at 100° C.):    35+/−3 MU; M_(n)=80,000 g/mol; M_(w)=260,000 g/mol.

In the glove box, the Parr reactor was charged with 5.0 mL of NBRsolution (5 wt.-% in C₆H₅Cl) and catalyst 1, 3, 4, 5, 6, 8, 10, 11 or 12respectively (2.5 mg, ca. 2.5 μmol and 1.0 mg, ca. 1.0 μmol). Thereactor was taken out of the glove box and purged with 20 bar H₂ (fourtimes). The temperature was set at 80° C. and the pressure at 40 bar ofH₂. After the temperature was equilibrated to 80° C., the pressure wasincreased to 50 bar and the reaction was carried out for 20 hours whilestirring vigorously. The hydrogenation was stopped by cooling down thereactor to room temperature and venting H₂. The polymer wascharacterized by FT-IR (thin film on KBr plates).

B.2 Hydrogenation of 1-hexene

In a glove box, a sample of the metal complex 10 (0.005 g, 5 μmol) or 11(0.005 g, 5 μmol) or 12 (0.005 g, 5 μmol), deuterated solvent (0.5 mL)(C₆D₆ for 12 and CD₂Cl₂ for 10 and 11) and substrate i.e. 1-hexene (0.1mmol) were combined in a vial. The mixture was transferred to a J. Youngtube and the J. Young tube was sealed. On a Schlenk line, the reactionmixture was degassed four times using the freeze-pump-thaw method. Thesample was then frozen once more in liquid nitrogen and 4.053 bar of H₂was added. The J. Young tube was sealed again and warmed to roomtemperature and then placed in an oil bath pre-heated to 45° C. ¹H-NMRspectra were measured at appropriate intervals and relative integrationof substrate and product peaks were used to determine the composition ofthe mixture.

B.3 Hydrogenation of Styrene

Identical procedure as in B.2 was followed.

B.4 Hydrogenation of Phenylacetylene

Identical procedure as in B.2 was followed.

B.5 Hydrogenation of Acrylaldehyde

Identical procedure as in B.2 was followed.

B.6 Hydrogenation of Acrylonitrile

Identical procedure as in B.2 was followed.

B.7 Hydrogenation of 3-buten-2-One

Identical procedure as in B.2 was followed.

B.8 Hydrogenation of Allylamine

Identical procedure as in B.2 was followed.

B.9 Hydrogenation of 1-vinylimidazole

Identical procedure as in B.2 was followed.

TABLE 1 Hydrogenation of NBR (Perbunan ® T3435) (80° C.; 50 bar; 20 h).Catalyst HNBR (hydrogenated molar nitrile rubber) mass loading NBRdegree of hydrogenation Mn Mw No. [g/mol] [μmol] [mg] [g] [%] [g/mol][g/mol] PDI IE 1 1,071.92 2.5 2.7 0.55 ~100 97.364 232.181 2.38 IE 11,071.92 1 1.1 0.55 ~95 52.739 100.303 1.90 IE 2 945.68 2.5 2.4 0.55 ~9574.040 158.170 2.14 IE 2 945.68 1 1.0 0.55 ~90 39.467 101.758 2.58 IE 3947.70 2.5 2.4 0.55 ~95 110.927 217.663 1.96 IE 3 947.70 1 1.0 0.55 ~9061.491 139.988 2.28 IE 4 987.76 2.5 2.5 0.55 ~95 55.417 152.882 2.76 IE4 987.76 1 1 0.55 ~90 37.534 100.500 2.68 IE 5 989.78 2.5 2.5 0.55 ~9593.650 174.899 1.86 IE 5 989.78 1 1 0.55 ~90 89.473 170.973 1.91 IE 6989.71 2.5 2.5 0.55 ~100 105.641 194.436 1.84 IE 6 989.71 1 1 0.55 ~10049.874 97.546 1.96 IE 8 1,013.68 2.5 2.5 0.55 ~100 104.476 201.100 1.92IE 8 1,013.68 1 1 0.55 ~95 45.431 89.506 1.97 CE 10 1,035.64 2.5 2.50.55 No conversion nd nd nd CE 10 1,035.64 1 1 0.55 No conversion nd ndnd CE 11 909.40 2.5 2.3 0.55 No conversion nd nd nd CE 11 909.40 1 10.55 No conversion nd nd nd CE 12 911.41 2.5 2.3 0.55 No conversion ndnd nd CE 12 911.41 1 1 0.55 No conversion nd nd nd nd = notdeterminable; IE = inventive example; CE = comparative example The useof complexes of general formula (I) comprising arylphosphine ligandssuch as triphenylphosphine ligands prevents the hydrogenation ofunsaturated polymers like NBR.

TABLE 2 Hydrogenation of alkenes with catalysts 10, 11 and 12^(a).t/yield t/yield t/yield Substrate product No. (h,/%)^(b) No. (h,/%)^(b)No. (h,/%)^(b) 1-hexene hexane 10 4/100 11  6/100 12  6/100 styreneethylbenzene 10 8/100 11 14/100 12 16/100 phenylacetylene ethylbenzene10 8/100 11 24/100 12 24/96^(c) acrylaldehyde propionaldehyde 10 3/10011  8/100 12 12/100 acrylonitrile propionitrile 10 22/100  11 24/100 1224/86 3-buten-2-one 2-butanone 10 16/100  11 18/100 12 20/100 allylaminepropylamine 10 8/100 11 14/100 12 16/100 1-vinylimidazole1-ethylimidazole 10 12/100  11 24/86  12 24/71 ^(a)Conditions: 0.10 mmolof substrate and 5 mol % of catalyst in CD₂Cl₂ or C₆D₆ at 45° C. under 4bar of H₂. ^(b)Yields were determined by ¹H-NMR spectroscopy. ^(c)4% ofthe product was observed to be styrene.

The complexes 10, 11 and 12 show hydrogenation of small molecules like1-hexane, styrene, phenylacetylene, acrylaldehyde, acrylonitrile,3-buten-2-one, allylamine and 1-vinylimidazole.

The invention claimed is:
 1. A ruthenium-based complex catalystaccording to general formula (I)

wherein R is independently of one another hydrogen, hydroxy, thiol,thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro,carboxylic acid, disulphide, carbonate, Isocyanate, carbodilmide,carboalkoxy, carbamate, halogen, straight-chain or branchedC₁-C₁₀-alkyl, C₆-C₂₄-aryl, or together with the carbon atoms to whichthey are bound form a C₆-C₁₀-cycloalkyl or C₆-C₁₀-aryl substituent,alkyl thiolate, aryl thiolate, B(R³)₂ or B(R³)₃, whereas R³ is alkyl,aryl, alkoxy or aryloxy or CF₃, n is 0 to 4, R¹ is straight-chain orbranched C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₂₄-aryl,C₁-C₁₀-alkylsulphonate, or C₆-C₁₀-arylsulphonate, R² is hydrogen,straight-chain or branched C₁-C₁₀-alkyl, C₃-C₁₀-cycloalkyl, C₆-C₂₄-aryl,C₁-C₁₀-alkylsulphonate, C₆-C₁₀-arylsulphonate, X is an anionic ligand,and Y¹ and Y² are identical or different and are each aC₁-C₁₀-alkylphosphine ligand, C₃-C₂₀-cycloalkylphosphine ligand, asulfonated C₁-C₁₀-alkylphosphine ligand, a C₁-C₁₀-alkylphosphiniteligand, a C₁-C₁₀-alkylphosphonite ligand, a C₁-C₁₀-alkyl phosphiteligand, a C₁-C₁₀-alkylarsine ligand, a C₁-C₁₀-alkylamine ligand, asubstituted or not substituted pyridine ligand, a C₁-C₁₀-alkyl sulfoxideligand, a C₁-C₁₀-alkyloxy ligand or a C₁-C₁₀-alkylamide ligand, each ofwhich may be substituted by a phenyl group which may in turn besubstituted by a halogen, C₁-C₅-alkyl or C₁-C₅-alkoxy group.
 2. Thecatalyst according to claim 1, wherein: R is independently of oneanother hydrogen, halogen, nitro, methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, sec-butyl or tert-butyl, phenyl, or together withthe carbon atoms to which they are bound form a C₆-C₁₀-cycloalkyl orC₆-C₁₀-aryl substituent, alkyl thiolate, aryl thiolate, B(R³)₂ or B(R³⁾₃, whereas R³ is alkyl, aryl, alkoxy or aryloxy or CF₃, N is 0 to 4, R¹and R² are identical or different and are each methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl or neopentyl,cyclohexyl, adamantyl, phenyl, methanesulphonate, p-toluenesulphonate,2,4,6-trimethylphenyl (Mes) or 2,4,6-triisopropylphenyl (Trip), X ishydride, halide, pseudohalide, alkoxide, amide, triflate, phosphate,borate, straight-chain or branched C₁-C₃₀-alkyl or C₆-C₂₄-aryl,carboxylate, acetate, halogenated acetate, halogenated alkylsulfonate,tosylate or any weakly coordinating anionic ligands, and Y¹ and Y² areidentical or different and are each C₁-C₁₀-alkylphosphine orC₃-C₂₀-cycloalkylphosphine ligand, a sulfonated C₁-C₁₀-alkylphosphineligand, a C₁-C₁₀-alkylphosphinite ligand, a C₁-C₁₀-alkylphosphoniteligand, a ,C₁-C₁₀-alkyl phosphite ligand, a C₁-C₁₀-alkylarsine ligand, aC₁-C₁₀-alkylamine ligand, a substituted or not substituted pyridineligand, a C₁-C₁₀-alkyl sulfoxide ligand, a C₁-C₁₀-alkyloxy ligand or aC₁-C₁₀-alkylamide ligand, each of which may be substituted by a phenylgroup which may in turn be substituted by a halogen, C₁-C₅-alkyl orC₁-C₅-alkoxy group.
 3. The catalyst according to claim 1, wherein: R isindependently of one another, hydrogen, halogen, methyl, ethyl,n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl,phenyl, or together with the carbon atoms to which they are bound form aC₆-C₁₀-cycloalkyl or C₆-C₁₀-atyl substituent, or CF₃, n is 0 to 4, R¹and R² are identical or different and are each methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl, sec-butyl or tert-butyl, cyclohexyl,phenyl, 2,4,6-trimethylphenyl (Mes) or 2,4,6 triisopropylphenyl (Trip),X is hydride or halide, Y¹ and Y² are identical or different and areeach C₁-C₁₀-alkylphosphine or C₃-C₂₀-cycloalkylphosphine ligand, asulfonated C₁-C₁₀-alkylphosphine ligand, a C₁-C₁₀-alkylphosphiniteligand, a C₁-C₁₀-alkylphosphonite ligand, a C₁-C₁₀-alkyl phosphiteligand, a C₁-C₁₀-alkylarsine ligand, a C₁-C₁₀-alkylamine ligand, asubstituted or not substituted pyridine ligand, a C₁-C₁₀--alkylsulfoxide ligand, a C₁-C₁₀-alkyloxy ligand or a C₁-C₁₀-alkylamideligand, each of which may be substituted by a phenyl group which may inturn be substituted by a halogen, C₁-C₅-alkyl or C₁-C₅-alkoxy group. 4.A ruthenium-based complex catalyst according to general formula (I)

wherein: R is independently of one another, hydrogen, methyl or CF₃, nis 0 to 4, R¹ is methyl, R² is phenyl, 2,4,6-trimethylphenyl (Mes) or2,4,6-triisopropylphenyl (Trip), X is chloride, and Y¹ and Y² are eachtricyclohexylphosphine (PCy₃).
 5. A process for hydrogenating substratespossessing at least one carbon-carbon double bond, the processcomprising subjecting a substrate possessing at least one carbon-carbondouble bond to a hydrogenation reaction in the presence of the catalystaccording to claim
 1. 6. The process according to claim 5, wherein thesubstrate to be hydrogenated is selected from the group consisting ofterminal olefins, internal olefins, cyclic olefins, conjugated olefins,any further olefins having at least one carbon-carbon double bond andadditionally at least one further polar unsaturated double or triplebond and polymers having carbon-carbon double bonds.
 7. The processaccording to claim 5, wherein the substrate is selected from the groupconsisting of: hydrocarbon compounds with a terminal unsaturatedcarbon-carbon double bond having the general formula C_(n)H_(2n);hydrocarbon compounds with an internal unsaturated carbon-carbon doublebond having the general formula C_(n)H_(2n); cyclic hydrocarboncompounds with an unsaturated carbon-carbon double bond having a generalformula C_(n)H_(2n-2), hydrocarbon compounds with at least twoconjugated unsaturated carbon-carbon double bonds; and olefins having aunsaturated carbon-carbon double bond in the presence of at least oneother unsaturated polar bond.
 8. The process according to claim 5,wherein the substrate is a polymer having carbon-carbon double bonds,and the polymer comprises repeating units based on at least oneconjugated diene monomer.
 9. The process according to claim 8, whereinthe substrate is: a nitrile rubber comprising repeating units of atleast one conjugated dime and at least one α,β-unsaturated nitritemonomer, or a nitrile rubber comprising repeating units of at least oneconjugated diene and at least one α,β-unsaturated nitrile monomer andone or more further copolymerizable monomers.
 10. The process accordingto claim 5, wherein the hydrogenation is carried out at a temperature of0° C. to 200° C. with hydrogen gas at a pressure of 0.1 MPa to 20 MPa.11. The process according to claim 5, wherein the catalyst according togeneral formula (I) is used in a molar ratio of (0.01-0.20):1 based onthe substrate to be hydrogenated.
 12. The process according to claim 5,wherein the catalyst according to general formula (I) is used in a ratioof 0.005 phr to 2.5 phr catalyst based on the susbstrate wherein thesubstrate is a rubber polymer.
 13. The catalyst according to claim 4,wherein: R is it of one another hydrogen, methyl or CF₃, N is 0 to 1, R¹is methyl, R² is phenyl, 2,4,6-trimethylphenyl (Mes), or2,4,6-triisopropylphenyl (Trip), X is chloride, and Y¹ and Y² are eachtricyclohexylphosphine (PCy₃).
 14. The catalyst according to claim 3,wherein: n is 0 to 2; X is hydride, fluoride, chloride, bromide oriodide, and for Y¹ and Y², the C₃-C₂₀-cycloalkylphosphine ligand istricyclohexylphosphine (PCy₃).
 15. The process according to claim 7,wherein the substrate is selected from the group consisting of: straightchain or branched hydrocarbon compounds with a terminal unsaturatedcarbon-carbon double bond having the general formulaC_(n)H_(2n);straight-chain or branched hydrocarbon compounds with aninternal unsaturated carbon-carbon double bond having the generalformula C_(n)H_(2n); cyclic hydrocarbon compounds with an unsaturatedcarbon-carbon double bond having a general formula C_(n)H_(2n-2);straight-chain or branched hydrocarbon compounds with at least twoconjugated unsaturated carbon-carbon double bonds; and olefins having atleast one terminal, internal, cyclic or conjugated carbon-carbon doublebond and at least one further unsaturated polar bond.
 16. The processaccording to claim 15, wherein the substrate is selected from the groupconsisting of: 1-hexene; 2-hexene; cyclohexene; styrene; and olefinswith at least one terminal, internal, cyclic or conjugated carbon-carbondouble bond and at least one further unsaturated polar bond selectedfrom carbon-nitrogen, carbon-phosphorus, carbon-oxygen, andcarbon-sulfur unsaturated polar bonds.
 17. The process according toclaim 9, wherein the substrate is a nitrile rubber comprising repeatingunits of; at least one conjugated diene selected from the groupconsisting of 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, piperyleneand mixtures thereof, at least one α,β-unsaturated nitrile selected fromthe group consisting of acrylonitrile, methacrylonitrile,ethacrylonitrile and mixtures thereof, and of no or one or more furthercopolymerizabie monomers selected from the group consisting ofα,β-unsaturated monocarboxylic or dicarboxylic acids, their esters oramides.
 18. The process according to claim 10, wherein the hydrogenationis carded out at a temperature of 15° C. to 150° C. with hydrogen gas ata pressure of 1 MPa to 16 MPa.
 19. The process according to claim 11,wherein the catalyst according to general formula (I) is used in a molarratio of (0.01-0.05):1 based on the substrate to be hydrogenated. 20.The process according to claim 12, wherein the catalyst according togeneral formula (I) is used in a ratio of 0.025 phr to 2 phr catalystbased on the substrate.